The present invention relates to a projector which projects an image on a screen.
Recently, a projector is widely used for various applications, and it is desired to develop a compact projector having superior portability. Generally, in order to control the rise in the temperature of the projector due for example to a light source, the heated air in the projector must be exhausted by means of an exhaust fan. In many projectors, the exhaust fan and an exhaust port are closely placed, because of the demand for reducing the size of the projector.
There is also type of projector having an externally attached duct for preventing the exhausted air from blowing toward a person beside the projector. FIGS. 16A and 16B are respectively a perspective view and a side view showing an outer shape of a projector disclosed in a Japanese Laid-Open Patent Publication HEI 9-319007. As shown in FIG. 16A, a projector 101 has a projection lens 103 provided on the front of an enclosure 102 and an exhaust port 104 provided on the side of the enclosure 102. A duct 105 is detachably attached to the exhaust port 104. The duct 105 directs the exhausted air upward, so that the exhausted air does not blow toward the person beside the projector.
As shown in FIG. 16B, the duct 105 is attached to the enclosure 102, by inserting engagement pieces 106 formed at the end of the duct 105 into grooves 107 formed around the exhaust port 104, and by rotating the duct 105 in one direction. The duct 105 is detached from the enclosure 102, by rotating the duct 105 in a reverse direction, and by removing the engagement pieces 106 from the grooves 107.
FIGS. 17A and 17B are respectively a perspective view and a side view showing an outer shape of another conventional projector. In addition to the components described with reference to FIGS. 16A and 16B, inlet ports 201 are formed on the top of the enclosure 102. The outside air is taken through the inlet ports 201 and the inside air is exhausted through the exhaust port 104. Thus, the cooling effect is enhanced.
However, the above described conventional projectors have the following problems.
First, the projector in which the exhaust fan and the exhaust port are closely placed has a problem that a noise called xe2x80x9cwind noisexe2x80x9d is generated. In order to restrict the wind noise being generated, it is necessary to provide a large space between the exhaust fan and the exhaust port. However, if such a space is provided, it becomes difficult to reduce the size of the projector.
Additionally, in order to keep the exhaust fan operating properly, it is necessary to keep the temperature of a fan motor built in the exhaust fan within a suitable temperature range. Thus, generally, a reflector or the like is provided between a lamp used as a light source and the exhaust fan, to shield the exhaust fan from the radiation from the lamp. In order to reduce the number of components of the projector, it is preferable to eliminate such a reflector. However, to eliminate the reflector, the distance between the lamp and the exhaust fan must be increased, and therefore it becomes difficult to reduce the size of the projector.
Further, the projector 101 having the externally attached duct 105 as shown in FIGS. 16A through 17B is not convenient to use, since the duct 105 needs to be attached to the projector and the direction of the duct 105 needs to be adjusted each time the projector 101 is used. Moreover, this projector 101 has another problem that the attached duct 105 impairs the appearance of the projector 101.
In addition, the projector having the inlet ports as shown in FIGS. 17A and 17B has a problem that the dust or the like enters into the projector through the inlet ports when the projector is not used, and degrades the displayed image.
This invention is intended to solve the above described problems, and an object of the present invention is to provide a compact projector having excellent portability, to restrict the noise generated in the projector, and to reduce the number of components of the projector.
A projector according to the invention comprises an image projection unit which projects an image and has a light source. The projector further comprises a first casing in which the image projection unit is mounted, and a second casing combined with the first casing thereby to constitute an enclosure enclosing the image projection unit. The second casing is movable relative to the first casing, between an enlarging position where the volume of the enclosure is enlarged and a reducing position where the volume of the enclosure is reduced. The projector further comprises an exhaust port formed on the second casing.
According to one aspect of the invention, the projector further comprises an exhaust fan mounted to the first casing. The exhaust fan is made to rotate when the light source illuminates.
When the projector is not used, the size of the projector can be reduced by moving the second casing to the reducing position. Thus, the portability of the projector is enhanced. Further, when the projector is used, the second casing can be moved to the enlarging position to restrict the noise. Thus, the quietness of the projector is enhanced.
According to another aspect of the invention, the projector further comprises an exhaust fan mounted to the second casing. The distance between the exhaust fan and the light source is longer when the second casing is in the enlarging position than when the second casing is in the reducing position.
When the projector is not used, the size of the projector can be reduced by moving the second casing to the reducing position. Thus, the portability of the projector is enhanced. Further, when the projector is used, the temperature of the exhaust fan can be kept in a suitable range without using a reflector or the like, by moving the second casing to the enlarging position so that the distance between the exhaust fan and the light source increases. Thus, the reflector is eliminated and therefore the number of the components of the projector is reduced.